1. Field of the Invention
This invention relates to a process for preparing a mixture of polycyclic aromatic polycarboxylic acids that is substantially soluble in acetone and substantially soluble in water which comprises subjecting a slurry containing coal to reaction with aqueous nitric acid in an atmosphere containing molecular oxygen, mechanically separating the solids in the resulting slurry, separating nitric acid and water from the resulting filtrate and then extracting the remainder of said filtrate with a polar solvent to obtain said mixture of polycyclic aromatic polycarboxylic acids substantially soluble in acetone and substantially soluble in water.
2. Description of the Prior Art
In our U.S. Patent application Ser. No. 814,217, entitled Organic Acids and Process for Preparing Same, filed July 5, 1977, which application is incorporated herein by reference, we disclosed a process for preparing a mixture of polycyclic aromatic polycarboxylic acids that is substantially soluble in acetone and substantially soluble in water which involved subjecting a slurry containing coal to reaction with aqueous nitric acid, mechanically separating the solids in the resulting slurry, separating nitric acid and water from the resulting filtrate and then extracting the remainder of said filtrate with a polar solvent to obtain a said mixture of polycyclic aromatic polycarboxylic acids substantially soluble in acetone and substantially soluble in water.